1. Field of the Invention
The present invention relates to a circuit breaker and a method of fabricating a pin for a switching mechanism thereof, and more particularly, to a circuit breaker having a pin capable of hinge-coupling and insulating a link of a switching mechanism for switching a moving contact and a method of fabricating a pin for the switching mechanism thereof.
2. Description of the Conventional Art
In general, circuit breaker is a type of electrical device for manually switching an electrical circuit using a handle, or sensing an abnormal current when a short current or fault current occurs to automatically break a circuit, thereby protecting a load device and circuit.
Hereinafter, a circuit breaker in the related art will be described below with reference to FIG. 1.
A circuit breaker in the related art may include a stationary contact 10, a movable contact 20 rotatably provided to be brought into contact with or separated from the stationary contact 10, and a switching mechanism 30 configured to revolve the movable contact 20 to switch a circuit within a case (not shown).
The switching mechanism 30 may include a pin for hinge-coupling a shaft 74 rotatably provided therein, a transfer link 90 configured to transfer a driving force from the shaft 74 to the movable contact 20, and a pin 80 for hinge-coupling the shaft 74 to the transfer link 90.
In this case, referring to FIG. 1, the circuit breaker is formed with a plurality of phases, and a pair of the stationary contact 10 and the movable contact 20 are provided for each phase.
Accordingly, the switching mechanism 30 should be formed with a structure capable of switching a plurality of the movable contacts 20.
Consequently, the movable contact 20 and the transfer link 90 hinge-coupled to the movable contact 20 are provided for each phase.
Furthermore, a shaft arm 74b protruded in a radial direction from a shaft rotation axis 74a is formed on the shaft 74 for each phase.
The shaft arm 74b is hinge-coupled to the transfer link 90 for each phase.
Here, the pin 80 is formed of an insulating material to prevent dielectric breakdown from occurring from a particular phase to another phase.
According to the foregoing configuration, when a handle of the switching mechanism 30 is rotated in a counter clockwise direction on the drawing and closed, the movable contact 20 and the switching mechanism 30 are brought into contact with each other by the switching mechanism 30 to connect a circuit.
On the contrary, when an abnormal current occurs on a line, the trip mechanism (not shown) is operated to release the restriction of a latch 62 of the switching mechanism 30.
When the restriction of the latch 62 is released, the movable contact 20 is rapidly separated from the stationary contact 10 by an elastic force of the tension spring 50 of the switching mechanism 30.
On the other hand, when an abnormal current is removed, the movable contact 20 and the stationary contact 10 are brought into contact with each other again through the manipulation of the switching mechanism 30. I
During the process, the pin 80 hinge-couples the shaft 74 to the transfer link 90 to transfer a driving force received from the shaft 74 to the movable contact 20 through the transfer link 90.
Furthermore, the pin 80 insulates the shaft 74 from the transfer link 90 for phase-phase insulation.
However, according to a circuit breaker in the related art, a wear resistance of the pin 80 formed of an insulating material is lower than that of the shaft 74. In other words, a hardness of the pin 80 is lower than that of the shaft 74. Due to this, when switching operations are repeated, a contact portion of the pin 80 to the shaft 74 is worn and damaged. As a result, a contact pressure between the movable contact 20 and the stationary contact 10 may be reduced, thereby increasing a contact resistance thereof.